Generating visible light with traditional light sources, such as incandescent or fluorescent light sources, is inefficient because thermal energy is also produced as by-product of the process. The wasted thermal energy is generally directed away from the light source in the direction of the radiant beam of light. Fixtures such as light shades or reflectors, or even the target illuminated by the light source, receive the wasted thermal energy, and consequently, rise in temperature. In some instances, the rise in temperature can reduce the useful life of a product. Further, the arrangement of traditional light sources are limited to designs that can withstand the wasted thermal energy. In underwater applications, wasted thermal energy is typically dissipated into the water, however, this does not prevent the light fixtures from having a relatively short life due to this excess heat.
It is also known to use fiber-optic cables for underwater lighting, but fiber-optic lighting is expensive and difficult to install, and is not suitable for the retro-fitting of existing pools. Additionally, the fiber-optic light fixtures are not as bright as traditional incandescent light fixtures, and are therefore not well used in pool and other underwater lighting applications.
In contrast to traditional light sources, solid state lighting, such as light emitting diode (“LED”) fixtures, are more efficient at generating visible light than many traditional light sources. However, single LED lights are typically not bright enough for illuminating objects or for use in pool and other underwater lighting. In order to use LEDs for illumination, a cluster of LED fixtures must be provided. Although LEDs do not generally radiate heat in the direction of the beam of light produced, implementation of LEDs for many traditional light source applications has been hindered by the amount of heat build-up within the electronic circuits of the LEDs. This heat build-up is particularly problematic as more LEDs are added to a cluster. Heat build-up reduces LED light output, shortens lifespan and can eventually cause the LEDs to fail.
Accordingly, heat sinks have been used to dissipate heat away from LEDs; however, in the past, LEDs have been thermally coupled to heat sinks with adhesive tapes. The use of adhesive tape introduces several problems, such as the labor and time intensive process of providing tape for each individual LED. Further, adhesive tapes are susceptible to being displaced during the assembly process, resulting in less than optimal heat dissipation. Particular problems arise when the light fixture is intended for use underwater in a swimming pool, spa, fountain, sink or other water feature. Not only must a heat sink be provided, it must be able to withstand being submerged. For example, it is not possible to use adhesive tape to connect an LED to a heat sink in a fixture designed to be submerged, because the adhesive can dissolve in water, causing the connection to the heat sink to be broken.
LED light engines have recently become available, which supply multiple LED lights in an array. The light engines make it possible to provide a high lumen light using LEDs, and it is desirable to use such light engines in swimming pool, spa and other underwater lighting. However, the management of heat generated by the light engines is critical to maintaining the performance of the LED array, and it is therefore desirable to be able to package an LED light engine in such a way that it can be used in underwater applications.